US2717901A

US2717901A - Process for degreasing wool and the recovery of wool grease

Info

Publication number: US2717901A
Authority: US
Inventors: Daniel P Norman
Original assignee: Pacific Mills
Current assignee: Pacific Mills
Priority date: 1951-01-31
Filing date: 1951-01-31
Publication date: 1955-09-13
Anticipated expiration: 1972-09-13

Description

Sept. 13, 1955 D. P. NORMAN 2,717,901

PROCESS FOR DEGREASING WOOL AND THE RECOVERY OF WOOL GREASE Filed Jan. 3l 1951 f2? l l /0 j 2 f8 0 4 l 1 24 I 1 Grease O i =:=.=.=.Vs-''= laad DWL 32' 26 365| 0 l 206 42 fcdsa B l V L 1 u l 2 4 1586 l Ho/'h/afel" 9c Grease T l .51% 552. 382' I l'ozL h/aer' 5? /sd Ge 1 INVENTOR.

UnitedStates Patent Oiice 2,7 17,9 l Patented Sept. 13, 1955 PROCESS FOR DEGREASING WOOL AND THE RECOVERY 0F WOOL GREASE Daniel P. Norman,

Ipswich, Mass., assigner to Pacino Mills, Lawrence,

The present invention relates to the degreasing of wool and more particularly to a solvent extraction process of this character and to the processing of mixtures of wool grease, solvent, water and raw wool grease contaminants to recover wool grease therefrom.

An object of my invention is to provide a process for removing superfluous grease from raw wool to prepare it for textile uses.

A further object is to provide improved recovery processes for recovering wool grease of high quality from mixtures of wool grease, water and the contaminants usually associated with raw wool.

In the accompanying drawing, I have illustrated my process with a number of variants, A, B, `C, D, E and F by which it may be practiced.

The raw wool is extracted with tetrachlorethylene in any suitable way and my invention is not confined to any particular extraction procedure. Referring to the drawing, the raw wool may be fed at 1 to a wool degreasing apparatus indicated at 2 in which the wool is treated with tetrachlorethylene to leach the grease therefrom and from which the wool is discharged at 4. The degreasing apparatus 2 preferably includes condensing equipment 2a for recovering the vapors of the tetrachlorethylene evaporated from the wool and from which the condensed tetrachlorethylene is recycled for reuse.

In my degreasing process, the tetrachlorethylene supplied to the degreasing apparatus 2 contains a regulated proportion of Wool grease for the purpose of limiting the amount of grease leached from the wool. This regulation, in my process, can be so controlled as to leave in the wool the desired amount of grease, usually about 1% of its weight of wool grease. For this purpose, tetrachlorethylene containing wool grease is fed from the tank 6 to a proportioning meter 8 where it is mixed with substantially pure tetrachlorethylene from tank 10. A feed line 12 to the tank is supplied with condensed tetrachlorethylene from the degreasing machine condensers 2:1 through line 14, with make-up tetrachlorethylene, if and when necessary, from a line 16, or with tetrachlorethylene recovered from the wool grease, as will hereinafter be described, from a line 18.

According to the variant of my process illustrated at A in the drawing, the liquid extract from the degreasing machine 2, consisting largely of tetrachlorethylene and containing suint, other usual raw wool grease contaminants, small amounts of water and about 6% of its weight of wool grease, is led through line 20 and line 20a into a settling tank 22. A centrifuge 24 is included in the line 20 for the removal of suspended solids but may be omitted in this modification. In the settling tank 22 the extract, after standing about 48 hours, separates relatively cleanly by dilerence in specific gravity, into three layers, a bottom layer 26 consisting primarily of suspended solid contaminants, a middle layer 28 made up principally of tetrachlorethylene but containing a small amount of wool grease, and an upper layer 30 which is rich in wool grease. The bottom layer, with most wools,

will be relatively small and particularly so if the centrifuge 24 is employed. The middle or tetrachlorethylene layer constitutes the largest fraction, of the order of of the total. In the course of about 48 hours the upper or grease-rich layer, in the case of an extract originally containing 6% by weight of grease, will contain approximately 25 %*40% of its weight 0f wool grease.

rthe lower layer 26 is withdrawn at 32 and either distilled to recover solvent therefrom, processed to recover chemical components such as potassium salts, or discarded.

The upper layer 30 is decanted by withdrawing it through a line 34 and passed to distillation apparatus indicated schematically at 36a in which the tetrachlorethylene is removed from the grease by procedures wellknown in the art. From the still the tetrachlorethylene passes through the lines 18a, 18 and 12 to the tank 10 for reuse.

The middle portion is withdrawn and conducted through line 38a to the line 38 and thence to tank 6 for reuse.

According to the variant illustrated at B, the extract from the degreasing machine is passed through the centrituge 24 to remove the greater part of the solid contaminants therefrom and then instead of going to a settling tank, is conducted through line 20 and 20h to a high speed or ultra centrifuge 4t) of the Sharples or Podbielniak type in which it is separated by difference in specific gravity into a concentrated miscella and a dilute miscella corresponding respectively to the grease-rich portion 3i) and the tetrachlorethylene-rich portion 28 which are formed in the settling tank 22. The concentrated miscella is carried through a line 42 to distillation apparatus 36h and the dilute miscella passes through the lines 38b and 38 to the tank 6 for reuse. The grease content of a dilute miscella is thus supplied to line 38 to prevent excessive leaching of grease from the wool in extractor 2.

In the variants of my process just described, the volume of solvent which remains to be removed from the grease by distillation is markedly small as contrasted with the proportion of solvent which must be so removed in known solvent degreasing and grease recovery processes.

ln the modification illustrated at C in the drawing, the miscella from the centrifuge 24 is conveyed through lines 2t) and 29C to a mixing and agitating Washer 50c in which it is mixed with hot Water and vigorously agitated. therewith to leach out water-soluble contaminants. Such a miscella containing less than about 10% of wool grease can be washed with water, to extract substantially all of the water-soluble contaminants, principally suint, without forming an emulsion of such stability as to prevent economical separation of the grease therefrom. Accordingly, from the washer 50c the water-grease-tetrachlorethylene miscella passes through line 52e to a Supercentrifuge 54e which separates the aqueous phase containing the water-soluble contaminants, which is discarded as indicated. The remaining portion, consisting of tetrachlorethylene and grease with the non-water-soluble contaminants, is discharged from centrifuge 54C into the line 56C. The water-washed tetrachlorethylene-greasemiscella flowing into line 56C divides into two portions, one passing by line 5S to a still 36e and the other by line 38e to line 3S and thence to tank 6 for reuse. The solvent vapor from the still is conducted through lines 18C and 1S to tank 16 for reuse.

Tetrachlorethylene-grease miscellas which have been water washed and then separated from the water containing the Water-soluble contaminants, as in variant c, can, l have found, be further puried by passing them through an adsorption column to remove color-forming comf ponents of the wool grease. This is illustrated in Modification D, in which the miscella from the centrifuge 24 passes through

lines

20 and 20d to a washer 50d and thence by line 52d to supercentrifuge 54d. The miscella vfrom line 56d yfrom the centrifuge is divided into two portions as before, one going directly byline 38d tothe lline 38 and tank 6, and the other to a still. Since the miscella now has been water washed, the branch line 60 to the still 36d includes 'an adsorption column 62a' containing, for example, activated carbon, activated silica gel or activated clay 'for the removal from the grease of organic impurities capable of being removed by adsorption, particularly and importantly impurities which would discolor the grease at the necessary elevated distillation ternperatures. The te'trachlorethylene from the still is returned to tank through

lines

18d, 18 and 12.

Alternatively, as`illustrated at E, the miscella from the centrifuge 24 is conducted by

lines

20 and 20e to washer e, washed as before, discharged at 52e to the centrifuge 54e in which the water is removed, and is passed, through line 170, to a `supercentrifuge 72 where it is divided into a dilute miscella, which is recycled through lines 33e and 38 to the tank 6 for reuse, and a concentrated miscella which is discharged either directly through line '74 to the distillation apparatus 36e, or, since it has been waterwashed, through the line 76 to the adsorption column 62e and thence through line 78 to the distillation apparatus 36e. The vapors from the still 36C are returned through

lines

18e and 18 to the tank 10 for reuse.

I make use of a peculiar property of mixtures of wool grease, raw wool grease contaminant, water and tetrachlorethylene that when they have been washed with Water and separated from the resulting aqueous phase containing the water-soluble contaminants, including the suint, subsequent washing with water tends to form a mixture of two temporary emulsions which may be separated from each other by difference in specific gravity.

One of'these is primarily a water-grease emulsion and the other is a miscella of water, grease and tetrachlorethylene. When separated from the miscella, the water-grease emulsion can be resolved into water and grease by centrifugal treatment.

Thus, as is illustrated at F, the miscella from centrifuge 24 is conducted by

lines

20 and 20f to the washer 501, the mixture from the washer conducted by line S2f to centrifuge 54]c which removes the dirty wash water therefrom. The remaining water-washed miscella is conducted by line 80 to the adsorption column 62f and thence conducted through a line 82 to a washer 84, of the same general nature as the washer 50j, in which the miscella is again mixed with water and thoroughly agitated, resulting in the formation of a mixture of two emulsions, one

of which is primarily a grease-water emulsion and the r other of which is primarily a grease-tetrachlorethylenewater emulsion containing most of the tetrachlorethylene. This emulsion mixture is passed through line S6 to a supercentrifuge 88 for the purpose of resolving the mixture of emulsions. The separated grease-Water emulsion is discharged from centrifuge 88 into a line 9i) and the grease-tetrachlorethylene-water miscella is discharged, through a line 92, into another Washer 94, of the same character as the washer 84, where it is again washed and discharged to a supercentrifuge 96. In the supercentrifuge 96 the grease-water emulsion is separated from the grease-tetrachlorethylene-water emulsion and discharged to the line 90. The grease-tetrachlorethylene-water emulsion is discharged, through line 38f to line 3S to be returned to tank 6 for reuse.

I have found that the grease-water emulsions in line so obtained by repeated washing and sedimentation, are capable of resolution by centrifugation and accordingly the content of line 90 is led through line 98 to the supercentrifuge 100 wherein the water is removed lfrom the grease and discharged at 102 leaving a purified water and tetrachlorethylene free wool grease at 104.

Accordingly, in my variant F, the grease is recovered from the extract solely by a series of washing, sedimentation and centrifugation operations, thus eliminating completely the objectionable and expensive distillation step heretofore considered indispensable in the recovery of the vgrease in solvent extraction processes.

In solvent grease extraction processes heretofore known so far as I am aware, the distillation operation for removal of the solvent has been performed on the extract containing such color-forming ingredients, resulting in serious discoloration of the -grease product by polymerization or other change in those ingredients at the necessarily high temperatures of the distillation step. For this reason, wool grease obtained from the solventextraction type of wool degreasing process has been notorious for its low quality as respects color. For many uses ofthe grease, e. g. for cosmetic purposes, color is a primary consideration in determining the quality and value of the grease. vInmy `processes D, E and F such discolorotion is avoided.

l. have herein used the phrase separation by difference in specific gravity to denote both simple gravity separation, as by settling, and centrifugal separation, of either solids or liquids.

My processes are applicable generally to the recovery of wool grease from mixtures of such grease with water, water-soluble and insoluble contaminants and/or tetrachlorethylene. Thus wool grease may be recovered from the wool scouring liquor resulting from the conventional wool scouring operation employing a scouring bath of water, soap and alkalis by adding tetrachlorethylene to the scouring liquor and then employing any of the recovery procedures described above.

I claim:

l. The process for the recovery of wool grease from raw wool which comprises leaching the raw wool with tetrachlorethylene to extract wool grease therefrom, separating the liquid extract from the wool fibers, dividing the 'liquid kextract without addition of other material thereto, by treatment consisting of separation by difference in specific gravity, into a portion rich in wool grease and aportion rich in tetrachlorethylene, and separating the ,portion rich in wool grease from the other portion.

2. The process for the recovery of wool grease from raw wool which comprises -leaching the raw wool with tetrachlorethylene in a degreasing zone to extract wool grease therefrom, separating the liquid extract from the wool fibers, dividing the liquid extract without addition of other Vmaterial thereto, by treatment consisting of separation by difference in specic gravity, into a greaserich portion and a tetrachlorethylene-rich portion containing wool grease, separating the grease-rich portion from the tetrachlorethylene-rich portion, and returning the latter portion to the degreasing zone for reuse.

3. The process for the degreasing of raw wool and the purification and recovery of the wool grease which comprises leaching the raw wool with tetrachlorethylene in a degreasing zone to extract wool grease therefrom, separating the liquid extract from the wool fibers, removing solid contaminants .from the extract by difference in specific gravity, thereafter dividing the liquid extract without addition of other material thereto, by treatment consisting of separation by difference in specific gravity, into a grease-rich portion and a tetrachlorethylene-rich portion, separating the grease-rich portion from the other portion and removing tetrachlorethylene therefrom, and returning the tetrachlorethylene-rich portion to the degreasing zone for reuse.

4. The process for the recovery of wool grease from raw wool which comprises leaching the raw wool with tetrachlorethylene to extract wool grease therefrom, separating the liquid extract from the wool fibers, dividing the liquid extract without addition of other material thereto, by treatment consisting of separation by difference in specific gravity, into a portion rich in solid contaminants, la .portion rich in wool grease and a portion rich in tetrachlorethylene, separating the grease-rich portion and removing solvent therefrom by distillation.

5. The process for the degreasing of raw wool and the purification and recovery of the wool grease which comprises leaching the raw wool with tetrachlorethylene in a degreasing zone to extract wool grease therefrom, separating the liquid extract from the wool fibers, dividing the liquid extract without addition of other material thereto, by treatment consisting of separation by difference in specific gravity, into a portion rich in solid contaminants, a portion rich in wool grease and a portion rich in tetrachlorethylene, separating the grease-rich portion and removing solvent therefrom by distillation, and returning the tetrachlorethylene-rich portion to the degreasing zone for reuse.

6. The process for the recovery of wool grease from raw wool which comprises leaching the raw wool with tetrachlorethylene in a degreasing zone to extract wool grease therefrom, separating the liquid extract from the wool fibers, removing solid contaminants from the extract by difference in specific gravity, thereafter dividing the liquid extract without addition of other material thereto, by treatment consisting of separation by difference in specific gravity, into a portion rich in solid contaminants, a portion rich in wool grease and a portion rich in tetrachlorethylene, separating the grease-rich portion and removing solvent therefrom by distillation, and returning the tetrachlorethylene-rich portion to the degreasing zone for reuse.

7. The process for the recovery of wool grease from raw wool which comprises leaching the raw Wool with tetrachlorethylene to extract wool grease therefrom,

separating the liquid extract from the wool fibers, removing solid contaminants from the liquid extract by difierence in specific gravity, thereafter dividing the extract without addition of other material thereto, by treatment consisting of separation by difference in specific gravity, into a portion rich in tetrachlorethylene and a portion rich in Wool grease, separating the latter portion and removing solvent therefrom by distillation.

8. The process for the degreasing of raw wool and the purification and recovery of the wool grease which comprises leaching the raw wool with tetrachlorethylene in a degreasing zone to extract wool grease therefrom, separating the liquid extract from the wool bers, removing solid contaminants from the liquid extract by difference in specific gravity, thereafter dividing the extract without addition of other material thereto, by treatment consisting of separation by difference in specific gravity, into a tetrachlorethylene-rich portion and a grease-rich portion, separating the grease-rich portion and removing tetrachlorethylene therefrom by distillation, and returning the tetrachlorethylene-rich portion to the degreasing zone for reuse.

References Cited in the le of this patent UNITED STATES PATENTS 1,170,962 Chambers Feb. 8, 1916 1,358,163 Koch Nov. 9, 1920 2,097,147 Dinley Oct. 26, 1937 2,421,094 Totney May 27, 1947 2,607,786 Derby Aug. 19, 1952

Claims

1. THE PROCES FOR THE RECOVERY OF WOOL GREASE FROM RAW WOOL WHICH COMPRISES LEACHING THE RAW WOOL WITH TETRACHLORETHYLENE TO EXTRACT WOOL GREASE THEREFROM, SEPARATING THE LIQUID EXTRACT FROM THE WOOL FIBERS, DIVIDING THE LIQUID EXTRACT WITHOUT ADDITION OF OTHER MATERIAL THERETO, BY TREATMENT CONSISTING OF SEPARATION BY DIFFERENCE IN SPECIFIC GRAVITY, INTO A PORTION RICH IN WOOL GREASE AND A PORTION RICH IN TETRACHLORETHYLENE, AND SEPARATING THE PORTION RICH IN WOOL GREASE FROM THE OTHER PORTION.